Pat Ireland Nixon, physician and historian, was born at Old Nixon, Guadalupe County, Texas, on November 29, 1883, the son of Robert Thomas and Frances Amanda (Andrews) Nixon. He graduated from Luling High School (1900), the Bingham School in Asheville, North Carolina (1902), and the University of Texas (1905). He received a medical degree from the Johns Hopkins University School of Medicine in 1909. After postgraduate work in Baltimore hospitals, mostly in gynecology, Nixon began a medical practice in San Antonio, on October 1, 1911. As a general practitioner, he attended patients for more than fifty years. He served on the medical staffs of Baptist Memorial, Nix Memorial, and Santa Rosa hospitals. He also helped found the Bexar County Medical Library during the years after he started his practice. He was president of the Bexar County Medical Association (1926) and the Texas Surgical Society (1956). As a member of the San Antonio Board of Health (first appointed in 1928), Nixon crusaded for improvements in local government and better public health programs in the Alamo city. He served on city or city-county health boards for two decades.
Nixon was the first physician to write extensively on the history of medicine in Texas, a field to which he contributed several articles and three books: A Century of Medicine in San Antonio (1936), The Medical Story of Early Texas, 1528–1853 (1946), and The History of the Texas Medical Association, 1853–1953 (1953). He was also editor of Southwest Texas Medicine from 1934 to 1938 and medical editor for the Handbook of Texas (1952). Nixon served as president of the San Antonio Historical Association (1941), the Texas State Historical Association (1946–49), and the Philosophical Society of Texas (1946). He was permanent director of medical history at the Bexar County Medical Library from 1944 to his death and in that position acquired a large number of rare books for the library.
On July 3, 1912, Nixon married Olive Gray Read of Mineola, Texas. They had four sons. As a devout Methodist, Nixon also wrote articles and books about his church and family. In 1957 he received two literary honors-the Summerfield G. Roberts and Clement E. Trout awards. In 1963 he received an honorary doctorate from Trinity University. Nixon donated his extensive collection of Texana to Trinity University in 1964. He died on November 18, 1965, and was interred in Sunset Memorial Park, San Antonio.